Lachaume P, Hitte C, Jouquand S, Priat C, Galibert F
UMR 6745 CNRS Université Blaise Pascal, Aubiere, France.
Anim Genet. 1998 Jun;29(3):173-7. doi: 10.1046/j.1365-2052.1998.00297.x.
We have identified the gene coding for the canine ortholog of the human keratin 9 protein using the inverse-polymerase chain reaction (PCR) strategy. Sequence comparison and structure analysis of the gene show marked similarity with the human gene. This gene spans about 7 kb and spreads over eight exons. In the dog gene, the reading frame is extended by 20 codons, the first in-frame stop codon being in exon 8 in the dog rather than in exon 7 as in humans. Alignment of human and dog predicted amino acid sequences confirms the high analogy, reaching 75% identity and 95% similarity in the rod domain. Interestingly, the glycine-loop motif number in the C-terminal V2 variable subdomain of the protein increases from 19 in human to 43 in dog, generating a size difference of 12 kDa between the two proteins. Due to its restricted expression pattern in mammalian epidermis, dog keratin 9 gene was a good candidate gene for the genetic palmoplantar hyperkeratosis observed in the Dogue de Bordeaux. However, no polymorphism associated with the pathology was detected within an affected Dogue de Bordeaux pedigree ruling out this hypothesis.
我们采用反向聚合酶链反应（PCR）策略，鉴定出了编码犬类人角蛋白9蛋白直系同源物的基因。该基因的序列比较和结构分析显示，其与人类基因具有显著相似性。此基因跨度约7 kb，分布于八个外显子。在犬类基因中，阅读框延伸了20个密码子，第一个框内终止密码子位于犬类的外显子8中，而非人类的外显子7。人类和犬类预测氨基酸序列的比对证实了高度相似性，在杆状结构域中，同一性达到75%，相似性达到95%。有趣的是，该蛋白C末端V2可变亚结构域中的甘氨酸环基序数量从人类的19个增加到犬类的43个，导致两种蛋白之间存在12 kDa的大小差异。由于犬角蛋白9基因在哺乳动物表皮中的表达模式受限，它是观察到的波尔多犬遗传性掌跖角化过度症的一个良好候选基因。然而，在一个受影响的波尔多犬家系中未检测到与该病理相关的多态性，排除了这一假设。
